Why mathematicians are obsessed with this luxury chalk

Hagoromo has been described as "the Rolls-Royce of chalk." The formerly Japanese, now Korean brand's chalk is known for its smooth consistency, its vibrancy, and being nearly dust-free. But the brand almost disappeared in 2015, which sent its loyal fans into a frenzy, buying up lifetime supplies before the factory shut down. Luckily, Shin Hyeong-seok, a Korean schoolteacher and former seller of Hagoromo chalk, formed a relationship with the company's president, Watanabe Takayasu, and decided to take over. The transition wasn't easy, but Hyeong-seok's dedication to Takayasu's original formulas and methodology kept the brand alive. But is that enough to ensure its future? We visited Sejongmall, where Hagoromo chalk is made, to find out.